An endoscope provided with an endoscope hood at the distal end of a slim insertion portion may be used. This endoscope hood includes a substantially cylindrical hood body. This hood body includes a fixation portion to be fixed to the distal end of the insertion portion of the endoscope. Furthermore, a protrusion protruding in the direction of the observational field of view of the endoscope is disposed at the end portion of this fixation portion. In the endoscope provided with such a hood, this endoscope hood prevents direct contact of a front-end lens surface of an observational optical system exposed at an end surface of the insertion portion distal end with a lumen medial wall surface.
Japanese Unexamined Utility Model Application Publication No. 56-75912 and Japanese Unexamined Patent Application Publication No. 59-93413 disclose configurations in which exhaust holes are provided on side wall portions of endoscope hoods in order to discharge filth and the like adhering to end surfaces of endoscopes.
The above-described Japanese Unexamined Utility Model Application Publication No. 56-75912 discloses an endoscope hood having a notch for serving an exhaust hole prepared by notching the hood up to the end surface of an insertion portion of the endoscope and a configuration in which a cylindrical hood body is notched in a slanting direction and the lowest part of the notch is flush with the end surface of an endoscope. The above-described Japanese Unexamined Patent Application Publication No. 59-93413 discloses a configuration in which a cylindrical hood body is notched in a slanting direction and the lowest part of the notch does not reach the end surface of an endoscope.